Manufacture of glutamic acid



COOL T0 6. MAY BE OM/TTED BEE T 4 CAKE L Y I SUGAR W-- April 10, 1945. c. L. ROYAL 2,373,342

MANUFACTURE OF GLUTAMIC ACID Filed Sept. 6, 1945 HOT STEFFENS WASTE Ca(OH)2 TH/N L/QUOR OR OTHER ALKAL INE F/L 75/? I CO2 OR OTHER AC/D H 7.0 CAKE D/SCAPD FILTER 1 4 /A7 LESS THAN noc. k EVAPORATOR K HIGHER H61 0/? OTHER AC/D AC/D/FY/NG a-z I COOL r 25C.

CAKE A/WNOAC/D D/SCARD CENTR/FUGE RECOVE/Qy4 cu/rAMlcAc/o PLAN T {MOTHER LIQUOR A F/LT/PATE DISCARD FILTER Patented Apr. l0, 1945 UNITED ST TES PATENT OFFICE Ceieatian L. Royal, Toied tel-national Minerals This invention relates to improvements in the manufacture of glutamic acid and is of particular value in connection with the recovery the glumatic acid which is contained in Bteilen's waste liquor (the liquor which remains as the end product to be discarded at the conclusion of the well-known Stefl'en's process for the recovery of sugar from the molasses or sirup remaining from one of the later stages of the usual process for manufacturing sugar from. the sugar beet). This invention is to a certain extent a substitute for, or an improvement upon, the process described in the Masuda et al. patent, No. 1,947,583, issued February 20, 1934:, and has certain advantages over the procedure set forth in said patent.

As Stei'iens waste water or liquor comes from the sugar beet factory, it is what is known as thin Steilens waste, having a water content of about 97%. The materials other than water are about .l% sugar and 35% alkaline material, for example KOH, NaOl-I, Ca(OH)a and about 2.55% of protein materials, principally glutamic acid, with much smaller amounts of other substances, including tyrosine, isoleucine, leucine, and betaine.

The purpose of the present invention is to recover the glutamic acid contained fens waste liquor.

The first step in the improved process is to add to the thin Stefiens waste liquor sumcient lime in the form of the oxide or the hydroxide to bring the pH of the Stefiens waste liquor up to about from 10.5 to 11.5. The alkalinized liquor is then heated to a temperature sumciently high for a sufficient length of time to effect necessary hydrolvzation or breaking down of the various protelniferous constituents. Usually, it is sumcient to hold the temperature of the alkalinized material preferably at 85 C. for about two and one-quarter hours.

The hydrolyzed liquor is then cooled to about 20 C. preferably. to permit certain of the unwanted constituents to crystallize out and these unwanted constituents may be separated by a filtration step, the solids being discardedt In certain cases this cooling and filtration step to.

remove a portion of the undesired materials may be omitted.

In any case, the hydrolyzed liquor is then neutralized. This neutralization of the hydrolyzed waste liquor may be effected in various ways, for example, by treating with various acid substances, such as carbon dioxide, phosphoric acid, or possibly sulfuric acid. This carbonatins in thin Stei- 0, Qhio, aeaignor to In- & Chemical Corporation. a corporation of New York Application September 6, 1943, Serial No. 501,856 3 Claims. (Cl. 260-627) 'step is eiiected in any desired type of mixing oi the hydrolyzed waste liquor, the carbonates which are formed being relatively insoluble. These insoluble carbonates and any other insoluble materials or precipitated materials which have been formed in any previous step of the process and are contained in the neutralized waste liquor,. may be separated in any desired type 01' filtration apparatus. and the solid matter is discarded. At this point the filtrate which contains the glutamic acid in solution is still mostly water containing a relatively low percentage oi glutamic acid.

The amount of Steffens waste liquor which is available in any area is limited by the capacity of the local beet sugar factory or factories in that area to produce this so-called waste material, but it is not economical to operate separate plants for the purpose of recovering glutamic acid from the limit amount of waste liquor produced in the various areas where the beet sugar factories are located. Hence, it is usually considered advantageous to establish a single large plant for the purpose of treating Steflens waste liquor produced by different beet sugar factories located in a group of widely spaced areas and collectively producing a suflicient amount of Steilen's waste liquor to make the 'glutamic acid recovery operation economically feasible. Hence,

in collecting the liquor at the point where the glutamic acid recovery is actually eflected, itis desirable that the Bteilens waste liquor be shipped and received in asconcentrated a condition as'possible; otherwise the freight charges would be prohibitive.

To this end, therefore. the neutralized and filtered thin liquor is concentrated to a specific gravity of approximately 1.3 or somewhat higher by means of a multi-eifect evaporator, the operation preferably being performed at a temperature of not more than about C. in the first eilect.

The concentrated glutamic acid liquor is shipped to the main glutamic acid plant and stored until it is ready to be processed further. Since it is in a neutralized condition, having a. pH of about 7.0, it is not necessary to take any particular precautions about the materials which are used in constructing the tanks or piping involved at this stage in the storage or handling of the concentrated liquor.

The next step in the further processing of liquor consists in introducing a batch into an acidifying tank or vat and to the batch there is added at this point a suificient supply of hydro- ,chloric acid or other appropriate acid such as sulfuric acid to bring the pH value of the liquor down to about 8.2, which is the lac-electric point of glutamic acid. This acidifying step is eilected at a temperature not to exceed 50' C.

The mother liquor resulting from the previous or final acidification step is then filtered or centrifuged, preferably at 50 C., to remove the inorganic salts which crystallised out during acidification. The filtrate or liquid coming from the centrifuge is then introduced into a large crystallizing vat, where it is allowed to stand'at room temperature for a sumcient length of time,

usually about a week. to enable the crude glutamic acid to crystallize. The resulting slurry is then removed from the crystallizing vat and treated in a filter, for example, of the filter-press type, and the filtrate is discarded: or if it con tains any substantial percentage of glutamic acid it may be recirculated through the system to salvage the residual acid.

The cake from the filtrate consists of somewhat impure glutamic acid crystals, which, if desired, may be further treated in any approved manner in order to remove impurities and improve the color. Usually, this further purification step involves treatment with caustic soda in order to produce mono sodium glutamate, which is the commercial form in which glutamic acid is usually sold.

In the drawing accompanying this application there is shown a fiow sheet disclosing the preferred procedure as above described.

The details herein described are illustrative of the preferred way in which I have heretofore successfully practiced the improved process. It will be understood that the process is capable of such variations as may be found within the scope of the appended claims.

I claim:

1. The improvement in the art of recovering glutamic acid from thin Steifen's waste liquor, which comprises adding to the waste liquor sufficient alkaline material to raise the pH to from 10.5 to 11.5, heating the liquor for a time and at a temperature suilicient to hydrolyze the proteiniferous constituents, then reducing the pH to about the neutral point of 7.0 by the addition of an acidic material, separating and discarding any solids present, evaporating sufiicient.

water to raise the specific gravity to about 1.3, adding to the liquor suiiicient acidic material to reduce the pH to about the lac-electric point of glutamic acid and permit the inorganic salts to crystallize, separating and removing the solid materials, holding the liquor at about room temperature or less for a sumcient length of time to permit the glutamic acid to crystallize and then aeparating the glutamic acid crystals from the quor. 2. The improvement in the art of recovering glutamic acid from thin Bteflens waste liquor, which comprises adding to the wasteliquor sufficient alkaline material to raise the pH to from 10.5 to 11.5, heating the liquor for a time and at a temperature equivalent to about two hours at 85 C. so as to hydrolyze the proteiniferous constituents, then reducing the pH to about the neutral point of 7.0 by the addition of an acidic material, separating and discarding any solids present, evaporating sumcient water to raise the specific gravity to about 1.3, adding to the liquor sumcient acidic material to reduce the pH to about the lac-electric point of giutamic acid and permit the inorganic salts to crystallize, separating and removing the solid materials, holding the liquor at about room temperature or less for a suilicient length of time to permit the glutamlc acid to crystallize and then separating the glutamic acid crystals from the liquor.

3. The improvement in the art of recovering gluthmic acid from thin Bteii'en's waste liquor, which comprises adding to the waste liquor sufficient calcium hydroxide to raise the pH to from 10.5 to 11.5, heating the liquorfor a time and at a temperature equivalent to about two hours at 85 C. so as to hydrolyze the proteiniferous constituents, then reducing the pH to about the neutral point of 7.0 by the addition of carbon dioxide, separating and discarding any solids present, evaporating suflicient water to raise the specific gravity to about 1.3, adding to the liquor sufiicient hydrochloric acid to reduce the pH to about the iso-electric point of glutamic acid and permit the inorganic salts to crystallize, separating and removing the solid materials, holding the liquor at about room temperature or' less for a sufiicient length of time to permit the glutamic acid to crystallize and then separating the glutamic acid crystals from the liquor.

CELESTIANL. ROYAL. 

